Last night, the think tank Policy Exchange launched a new, baby think tank called the Capital City Foundation, "devoted to the continued prosperity and progress of London". Which is nice.

More importantly, however, the event featured a discussion of why, after years of post-war dominance, New York may be losing its crown as the unofficial capital of the world to London.

Ed Glaeser, native New Yorker, cities economist, and the delightfully named "Fred & Eleanor Glimp Professor" at Harvard, took to the stage, and explained why, in his opinion at least, London now has the edge over its rival. Granted, he was standing on a podium at the top of the Shard surrounded by Londoners at the time, but we like to believe he was being genuine nonetheless.

Now we know that urban populations can be hard to compare, because boundaries and definitions vary from city to city (seriously, we go on about this all the time), and the official definition of London is far more inclusive than the official definition of NYC: compare unofficial metropolitan populations, and New York almost certainly still has the edge.

But London's loss of status accompanied the loss of nearly a quarter of its population after the end of World War Two. The reverse in the population trend, then, implies a reverse in status, too.

2. Financial Sector

London's financial services sector is ever-so-slightly larger than New York's: it has around 340,000 employees to New York's 322,000. New York currently holds the top spot on the Global Financial Centres Index, however, with a two-point lead on London.

3. Education

Inner-city school normally have a reputation for poor results and crime, but London's schools are actually better than the national average. In the US, Glaeser says, "I can't think of a single major city in the states where this is the case". Cities including New York also have a far lower high school graduation rate than rural and suburban areas.

4. Geography

The world has shifted in London’s direction. In 1950, New York was perfectly positioned between California and Western Europe. Nothing else mattered much economically. The rise of the Arab World in the Seventies, the emergence of Eastern Europe in the Nineties and India’s post-2000 successes have all improved London’s geography relative to New York.

5. Government

This is a bit of a contentious one. Glaeser argues that the presence of central government in the UK's largest city is a good thing, not a bad one. He argues that Parliament's location means it's "friendly" towards big London infrastructure projects like Underground extensions or Crossrail.

On the other hand, London's city government has relatively little spending power compared to New York's. Only 35 per cent of New York's budget comes from central government grants; the rest is directly collected by the city through tax. Government control over London's finances is far stronger – it controls around 93 per cent of the capital's budget.

6. "Fun"

"London is just a fun place to be". Thanks, Ed.

7. Job Growth

Between 2001 and 2012, the number of people working in London grew by 17 per cent, while in New York it grew by only 3 per cent. Ha.

***

Glaeser did end his panegyric with a warning, however: "London is too expensive... we need to build lots and lots more housing" (we completely agree).

Next to the stage was London mayor Boris Johnson (also, as it happens, born in New York), who had some rather punchier stats on why London has the upper hand:

London has twice as many bookshops as New York.

We also have a quarter of the murder rate.

London has 240 museums to New York's 83.

Boris also tried to argue that London is home to more billionaires, but according to Business Insider, this isn't the case – London has 72 to New York's 110. To be honest, we'd rather have museums than billionaires anyway.

In pre-colonial times the Khoisan called Cape Town, //Hui !Gaeb, the place “where clouds gather” and Camissa “the place of sweet waters”. The future of the city will be shaped by water as it was in the past. But far more attention will need to be paid to the drivers and early warning signs.

The city has been experiencing well below average rainfall over the last two-and-a-half years resulting in limited recharge of its main storage dams. The Western Cape region has been declared a disaster area amid a prolonged drought.

Rainfall over the next six weeks will be crucial. Cape Town has a Mediterranean climate with rains falling in the winter months. If there are no major thunderstorms and no significant interventions to bolster supplies from alternate sources such as local aquifers, treated effluent or desalination, then the city could run out of water by the end of year, or in early 2018.

Cape Town is almost entirely dependent on surface water from six main storage dams. Despite population growth and increased demand for water, it has successfully used water demand management over the past 17 years to conserve water by fixing leaks, reducing water pressures, educating users and restricting outdoor water use. But on their own these steps are unlikely to be adequate to avert “day zero”. Alternate water supplies need to be added.

There are two things that Cape Town needs to get right: firstly, it must improve its early warning systems. That is easier said than done. The current drought arrived at a speed and without a confident warning from the scientific community. And, secondly, it must diversify its water supply and become less reliant on surface water supplies.

Early warning systems are not enough

Early warning signs of a pending drought in 2017 were not clear or loud enough to prompt timely actions. As a result, the city was caught relatively unaware. Perhaps the success of the water demand programme created a false sense of security.

Citizens, businesses, officials and politicians responded slowly to early warnings about potential shortages. This is for a number of reasons. Water is taken for granted; there are too many confusing messages about how to manage water; and there is general apathy to adapt to water scarcity because it doesn’t seem to be a priority until it’s in short supply.

Lessons from the 1996 to mid-2010 Australian Millennial Drought show that threat of drought was clearly understood following several severe droughts. Despite the experience, central government was only able to act once the risk became extreme. But then it acted swiftly, investing heavily in new technologies and infrastructure.

This meant substantial increases in the unit cost of water. But Australians understood, and accepted them.

Australians also learnt that there are no quick fixes. They are still working on new interventions and education 10 years after the drought ended.

The City of Cape Town is following a similar trend by investigating new technologies. But these will take time to implement and deliver water in sufficient volume to rescue the city from disaster. In the meantime, saving water is the only game in town in the hope that it will buy the city sufficient time until the next winter rainfall in 2018.

What should be done?

Drivers of water resources are like the cogs in a mechanical system. They turn slowly – some more so than others. Often they fail to attract political will or financial attention because water management is competing with other priorities and demands.

The immediate imperative is to ensure that Cape Town has sufficient water to serve 4m people with a collective demand of at least 500m litres per day. It will involve significant investment in alternative water supplies like stormwater, groundwater, seawater or treated wastewater for non-potable use.

But investment to alleviate the crisis must be carefully managed. Emergency spending can restart further crises which in turn could lead to installing new technologies that can’t be used because they are inappropriate or not affordable.

The long term plans need to focus on “climate proofing” the city to ensure that it becomes a water sensitive city. These plans should include treating the city as a catchment where water is collected naturally. Water should be captured and stored in rain tanks, detention ponds, in recharged groundwater and floodplains.

Plans should also include bringing new life to the city’s waterways and regenerating natural systems. This is about rethinking the value of springs, rivers and streams. These blue and green corridors are water sources as well as valuable in reducing urban temperatures.

The city must ensure it has proper plans in place that anticipate future events, such as prolonged changes in weather patterns, so that it can respond quickly. This must include being able to unlock investments and establishing private and government partnerships.

In addition, this drought is setting the conditions for the “new normal” in which citizens will need to become skilled at adapting to a sustainable threshold of water use.

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